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Varroa Destructor in Europe

The New Scientific Classification of the Different Species of Varroa

By Gudrun Koeniger

Translated from the "Deutsches Bienen Journal" November 2000, page 10,

by A.E.McArthur MIL

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Around 100 years ago in Java (Indonesia), Edward Jacobson found mites in a colony of the indigenous honey bee (Apis cerana), which he sent to the Leiden museum in Holland. In 1904 Dr A.C. Oudemans, the famous scientist, described these organisms as a new species and gave it the scientific name Varroa jacobsoni (Oudemans 1904). Nothing more was thought of this new species of mite for a long time. Only at the beginning of the 70's after massive damage had been caused to the Western honey bee Apis mellifera was the research into the Varroa mite intensified.

1. The Varroa mites on the Western honey bee, A.mellifera are larger than those on the Eastern A.cerana.

The research into Varroa mites concentrated initially on the mites in colonies of A.mellifera. The mite was present in great numbers and easy to find. Contrary to this the mites on A.cerana could only be found by deliberate searching using special, labour-intensive procedures. As a rule there were only a few mites present in A.cerana colonies making research extremely difficult. Despite this difficulty it soon emerged that the Varroa mites on our A.mellifera honeybees were noticeably larger than those present on A.cerana. This difference was explained by the fact that A.mellifera is larger than A.cerana and thus offered a more favourable environment.

2. The Varroa mites in the A.cerana colonies in Indonesia do not reproduce on A.mellifera brood.

The work done by Dr Anderson in Indonesia demonstrated that the mites from the indigenous bees in Java (the mites described in 1904 as Varroa jacobsoni!) could not reproduce in the brood of A.mellifera. This initially extremely surprising discovery pointed to considerable genetic differences in the different mite races.

3. The Mite currently known as "Varroa jacobsoni" consists of 18 genetically different Races.

The world wide search for genetic differences in Varroa mites infesting A.mellifera resulted in only a slight variation between two types (see diagrams!). The investigation of Varroa samples from the original host A.cerana using molecular methods (DNA sequencing) from all over Asia however showed great variations. Dr Anderson was able to identify 18 different types of mites (Haplotypes). He gave each type the name of the island or land in which it was found. Using computer aided computation 15 of these races were classified into 2 main groups, 3 races from the Philppines however, could not be classified.

One of the main groups embraces the mite races from the Asian sub-Continent, the mites from the Malaysian - Indonesian region fall into the other group. The genetic difference within the main groups amounts to less than 2%, however there is more than a 6% genetic , difference between the two main groups. This difference is so great, that classification, of both groups into different species was justified.

4. New Name for the Asian sub-Continent Mite Races: Varroa Destructor (Anderson, Trueman 2000)

In the new classification the main group from the Asian sub-continent receives the new title, Varroa destructor (Anderson, Trueman 2000). The other main group (Malaysian-Indonesian race) to which the originally described mites belong, should be now referred to as Varroa jacobsoni (Oudemans 1904).

5. World wide there are only Two Races of Varroa destructor which parasitise A. mellifera

The genetic research embraced mites from 32 countries and different continents, collected only from the Western honey bee A.mellifera. This research confirmed that only 2 Varroa races world wide had developed to become parasites on A.mellifera: the Korean and Japan/Thailand races. To date only the Korean race of Varroa destructor has been found in Europe (this relates also to the Varroa samples from Oberursel !). Furthermore the Korean race of Varroa destructor is present in the middle East, South Africa, North America and more recently in South America. In earlier research this mite race was designated as Russian type (R type) or Ger type.

On the other hand the Japan/Thailand race (Japan type or J type) of Varroa destructor is spread throughout North and South America. The Japan/Thailand type appears not to be so damaging to the Western honey bee as the Korean race.

A total of four Varroa species are already generally known: Varroa jacobsoni (1904), Varroa underwoodi (1987), Varroa rindereri (1996) and Varroa destructor (2000). It remains to be seen from further research whether the Varroa type in the Philippines is a separate species.

Sources

Anderson, D.L. Apidology 31 (2000), 281 - 292.

Anderson, D.L. Trueman, J.W.H. Experimental and Applied Acarology, 24 (2000), 165 - 189.

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